topic 2 cells and control biology

• where is the genetic material in a cell stored?

  in the nucleus
• in what form is genetic material stored?

  in the form of chromosomes in the nucleus
• what are chromosomes?


  long coiled up molecules of dna
• what is a diploid cell?

  a cell with a full set of dna
• what is a haploid cell?

  a cell with half a set of dna
• what does mitosis produce?

  2 daughter cells genetically identical to the original cell
• what is mitosis used for?


  for organisms to replace damaged cells
• an organism uses mitosis to reproduce what is this called?

  asexual reproduction
• what happens in interphase?

  the dna is copied and forms x shaped chromosomes to ready itself for mitosis
• what happens in prophase?

  • the chromosomes condense
  • membrane around nucleus breaks down
  • chromosomes lie free in cytoplasm
• what happens in metaphase?

  chromosomes line up at the cnetre of the cell
• wha t happens in anaphase?

  • cell fibres pull chromosomes apart
  • Chromosomes and their copies are pulled to different ends of the cell.
• what happens in telophase?

  membranes form around each of the sets of chromosomes

  these become the nuclei of the 2 daughter cells

  nucleus has divided
• what happens in cytokinesis?

  the cytoplasm and cell membrane divide forming 2 seperate cells
• what are the 3 processes plants/animals grow due to?

  Cell division, cell elongation, cell differentiation.
• what is cell dfferentiation?

  process where cell becomes specialised towards its job
• what is cell elongation?

  where plant cells expand

  makes cell bigger causes plants to grow
• what is a tumour?

  a mass of abnormal cells
• when is cancer?


  if a tumour invades/destroys surrounding tissue
• what are stem cells?

  undifferentiated cells
• what are embryonic stem cells?

  Undifferentiated cells that have the potential to develop into any type of cell in the body.
• where are adult stem cells found?

  in bone marrow?
• what do meristems produce?

  unspecialised cells able to form any cell type in the plant (essentially plant stem cells)
• why would we use embryonic stem cells in medicine?

  potential to create specialised cells to replace cells damaged by disease or injury
• what are some risks of using embryonic stem cells in medicine?

  • stem cells could uncontrollably divide causing a tumour to develop
  • viruses from the donors stem cells could be passed on to the recipient
• what is a risk of using embryonic stem cells in medicine?

  • patients body could recognize stem cells as a threat and trigger an immune response to try get rid of them
• what are sensory receptors?

  group of cells that detect a stimulus
• what is the the order of the cns coordinating a response to a stimulus?

  • stimulus is detected by receptors
  • stimulus in converted to a nervous impulse
  • impulse is sent along sensory receptors to CNS
  • CNS decides what to do
  • impulses travel through CNS along relay neurones
  • CNS sends info through a motor neurone
  • this neurone transports information to an effector
  • effector carries out response
• what are dendrites and dendrons job?

  to carry nerve impulse towards the cell body
• what are axons job?

  to carry nerve impulses away from cell body
• what is the purpose of an electrical insulator surrounding an some axons?

  • acts as an electrical insulator
  • speeds up electrical impulse
• what is a synapse?


  A synapse is a junction between two nerve cells where electrical or chemical signals are transmitted.
• what are neurotransmitters?


  chemicals that transfer nerve signals across the gap between cells
• what is a reflex?

  an automatic rapid response to stimuli in order to prevent/reduce chance of injury
• why is a reflex faster than a normal response to stimuli?

  as the nerurones in a reflex arc go through the spinal cord or an unconscious part of the brain it doesnt involves spending time to think about a response so its quicker